Remove source_deleted signal

...for now. Eventually, we will want a signal that tells us when sources
are no longer used, however that isn't just limited to when they're
deleted! This new signal should also be dispatched, for example, when
a source image field is set to `None`. Since none of the built-in
strategies are currently using the source_deleted signal, I've decided
to remove it until we have a more complete solution.

docs/advanced_usage.rst

@@ -122,7 +122,7 @@ The answer is that, when you define an ImageSpecField, ImageKit automatically
 creates and registers an object called a *source group*. Source groups are
 responsible for two things:
 
-1. They dispatch signals when a source is created, changed, or deleted, and
+1. They dispatch signals when a source is saved, and
 2. They expose a generator method that enumerates source files.
 
 When these objects are registered (using ``imagekit.register.source_group()``),

docs/caching.rst

@@ -33,7 +33,7 @@ Cache File Strategy
 -------------------
 
 Each ``ImageCacheFile`` has a cache file strategy, which abstracts away when
-image is actually generated. It can implement the following four methods:
+image is actually generated. It can implement the following three methods:
 
 * ``on_content_required`` - called by ``ImageCacheFile`` when it requires the
   contents of the generated image. For example, when you call ``read()`` or
@@ -42,7 +42,6 @@ image is actually generated. It can implement the following four methods:
   generated image to exist but may not be concerned with its contents. For
   example, when you access its ``url`` or ``path`` attribute.
 * ``on_source_saved`` - called when the source of a spec is saved
-* ``on_source_deleted`` - called when the source of a spec is deleted
 
 The default strategy only defines the first two of these, as follows:
 

imagekit/registry.py

@@ -1,6 +1,5 @@
 from .exceptions import AlreadyRegistered, NotRegistered
-from .signals import (content_required, existence_required, source_saved,
-                      source_deleted)
+from .signals import content_required, existence_required, source_saved
 from .utils import call_strategy_method
 
 
@@ -71,7 +70,6 @@ class SourceGroupRegistry(object):
     """
     _signals = {
         source_saved: 'on_source_saved',
-        source_deleted: 'on_source_deleted',
     }
 
     def __init__(self):

imagekit/signals.py

@@ -7,4 +7,3 @@ existence_required = Signal()
 
 # Source group signals
 source_saved = Signal()
-source_deleted = Signal()

imagekit/specs/sourcegroups.py

@@ -2,19 +2,19 @@
 Source groups are the means by which image spec sources are identified. They
 have two responsibilities:
 
-1. To dispatch ``source_saved``, and ``source_deleted`` signals. (These will be
-   relayed to the corresponding specs' cache file strategies.)
+1. To dispatch ``source_saved`` signals. (These will be relayed to the
+   corresponding specs' cache file strategies.)
 2. To provide the source files that they represent, via a generator method named
    ``files()``. (This is used by the generateimages management command for
    "pre-caching" image files.)
 
 """
 
-from django.db.models.signals import post_init, post_save, post_delete
+from django.db.models.signals import post_init, post_save
 from django.utils.functional import wraps
 import inspect
 from ..cachefiles import LazyImageCacheFile
-from ..signals import source_saved, source_deleted
+from ..signals import source_saved
 from ..utils import get_nonabstract_descendants
 
 
@@ -57,7 +57,6 @@ class ModelSignalRouter(object):
         uid = 'ik_spec_field_receivers'
         post_init.connect(self.post_init_receiver, dispatch_uid=uid)
         post_save.connect(self.post_save_receiver, dispatch_uid=uid)
-        post_delete.connect(self.post_delete_receiver, dispatch_uid=uid)
 
     def add(self, source_group):
         self._source_groups.append(source_group)
@@ -97,11 +96,6 @@ class ModelSignalRouter(object):
                     self.dispatch_signal(source_saved, file, sender, instance,
                                          attname)
 
-    @ik_model_receiver
-    def post_delete_receiver(self, sender, instance=None, **kwargs):
-        for attname, file in self.get_field_dict(instance).items():
-            self.dispatch_signal(source_deleted, file, sender, instance, attname)
-
     @ik_model_receiver
     def post_init_receiver(self, sender, instance=None, **kwargs):
         self.update_source_hashes(instance)